All posts

How to Corral Gemini for Agentic Coding

September 25, 2026

#AI#gemini#Software Engineering#Developer Tools#llm
How to Corral Gemini for Agentic Coding

Gemini has developed a bit of a reputation in the multi-agent space. I recently heard someone refer to it as the "idiot in the room" when it comes to long-term agentic coding. That is both unfair and a massive missed opportunity. The reality is that the Gemini Flash architecture is fundamentally different. It possesses serious capabilities, and when you factor in its token quotas and intro pricing—like the recent 3.8 Flash model at $0.75 per million input tokens—it is easily the best deal on the market if you can figure out how to drive it.

Stop Treating It Like Claude

If you hand Gemini a massive block of work and expect it to carry the whole load unattended, it will fail. That is the primary reason it gets a bad rap. Through my trials, the model consistently demonstrated specific strengths and glaring weaknesses. It excels at walking an operator through a list, one item at a time, and rapidly recording rulings. It is fantastic at redrawing screen designs as fast as you can react to them, and it gets clear decisions quickly, successfully capturing dozens of operator rulings in a single sitting.

However, it does not check its own facts or work through the downstream consequences of its design choices. It routinely fails to cross-reference its work against other established documents and has a habit of marking its own work as "approved," even when approval strictly belongs to the human operator. Because of these traits, you should never give Gemini long coding work it must carry alone, assign it independent reviews, or allow it to directly change git history.

The Winning Pattern: Bounded Work and Subagents

To get reliable code out of Gemini, you have to strictly bound its scope. Choose a real, low-complexity task with a clear red/green outcome and a small file footprint, avoiding architectural decisions, shared runtime orchestration, or broad refactoring. When dispatching the work, do not let Gemini run through the packet as a single author. Instead, force it to organize its workflow using subagents.

Tell Gemini to act as a top-level coordinator that reads the packet and builds a strict checkbox checklist for every acceptance criterion and verification command. The coordinator then delegates one coherent implementation unit to an author subagent. Afterward, a different subagent must review the committed candidate, read the actual diff, and challenge any missing assertions or scope drift. The coordinator reconciles the findings, but crucially, a subagent simply saying "done" does not mean the work is complete. You must independently inspect the diff and execute the specified checks yourself; never accept the model's self-reported pass. Remember that a wrong test oracle is a failure, even if every test technically passes.

The Multi-Model Orchestration Pipeline

Because I run multi-agent dispatch, I found that Gemini works best when paired with stronger models. The most effective pipeline pattern uses Gemini inside Antigravity for the conversational heavy lifting and rapid iteration with the operator. Once that is done, send Gemini's finished output to an independent reviewer, expecting it to get blocked on the first pass. Finally, hand the reviewer's findings to a stronger model like Claude or Codex for the fix pass. Instruct the stronger model that the operator's rulings stand, and if a finding collides with a ruling, the model must keep the ruling and report the collision.

Crafting the Dispatch Packet

Gemini requires a very specific approach to prompting. Google's own documentation emphasizes concise, direct instructions and explicit context. Place the concrete task at the end of the packet, after any long context. Put everything it needs directly in the packet, including source material and existing rulings, so the operator never has to point it at another file.

Crucially, Gemini will parrot the exact style of the dispatch packet it is given; if you hand it dense, jargon-heavy instructions, it will generate dense, unusable text. Write every sentence of the packet in the exact tone you want the output written, and provide one approved example of the target prose. Explicitly instruct it to show you the current text, show its proposed text, and ask for a yes, no, or reword.

Gemini is not the idiot in the room. It is a highly capable, ridiculously cost-effective workhorse. If you stop expecting it to act like Claude and start scaffolding it with strict checklists, subagent delegation, and stronger peer models for the final polish, it will absolutely get the job done.


Jason Vertrees is the founder of Heavy Chain Engineering, which helps lower middle-market vertical SaaS companies and PE firms turn scattered AI usage into measurable delivery leverage — 85% faster feature velocity, six-to-eight-week projects shipped in days. If you want help building an AI-native engineering organization, book an AI Delivery Assessment or email jason.vertrees@gmail.com.